1. Field of the Invention
The present invention relates to a mount structure and mount method for mounting an angular velocity sensor by use of lead frames.
2. Description of Related Art
Conventionally, this type of angular velocity sensor includes a package and an angular velocity sensing element, which includes an oscillator and is received in the package. Here, the angular velocity sensing element detects an angular velocity based on a detection vibration of the oscillator. The angular velocity sensor includes lead frames, which electrically connect with an exterior.
Conventionally, for example, Japanese Unexamined Patent Publication 2003-46479 corresponding to U.S. Pat. No. 6,880,399 discloses a mount structure, in which the above angular velocity sensor is coupled with a mount member through the lead frames. In this publication, the mount member is disposed such that the mount member surrounds an outer periphery of the package. Also, an outer peripheral end portion of the package is electrically connected with the mount member, which is located around the outer peripheral end portion, through the lead frames.
An oscillation angular velocity sensor detects the angular velocity by vibrating the oscillator and then sensing a displacement (i.e., a detected oscillation) of the oscillator due to a Coriolis force when the angular velocity is applied. The detected oscillation is normally a high-frequency oscillation, and the angular velocity is detected based on the above high-frequency oscillation.
Thus, an erroneous detection may occur in a case where a high-frequency external oscillation, which oscillates in an oscillation direction of the above detected oscillation, reaches the oscillator through the mount member and overlaps the detected oscillation. Therefore, it is needed that the high-frequency external oscillation, which oscillates in the oscillation direction of the detected oscillation, is reduced by a vibration control.
In case of a structure, where the angular velocity sensor is coupled with the mount member through the lead frames, the external oscillation that reaches the angular velocity sensor can be controlled when the high-frequency external oscillation is reduced by use of the lead frames. In order to attain this, it may be needed that the lead frames are longer and that a rigidity of the lead frames is reduced such that a resonance frequency in a spring-mass system, in which the lead frame serves as a spring and the angular velocity sensor serves as a mass, is reduced.
However, in the above conventional art, in a case where the lead frames are elongated to control the vibration, the lead frames greatly extend radially from the outer periphery of the package of the angular velocity sensor. Thus, a mount space for mounting the angular velocity sensor to the mount member disadvantageously becomes larger. As a result, the mount member becomes larger and the structure becomes larger.